This invention relates to the jaws of vises used for holding work pieces in machine tools such as drill presses and milling machines and the like. Heretofore, the positioning of a work piece between the usual solid jaws of a vise has involved tapping and/or pounding of said work piece into place while clamping the same. However, there are vise jaws which pull downward while clamping thereby to draw the work piece against the vise bed or onto parallels, as the case may be; and such jaws have involved inclined cam action that exerts downward force, guide pins limiting motion of a moveable jaw face, and various apparatus with springs for biasing the moveable jaws face into an inactive position when released. Although the prior art draw-down jaws have their advantages, they are lacking in various respects; the moving jaws have been restricted in motion in the belief that this was necessary to maintain parallelism; the apparatus involved with assembly has been exposed to chips and debris; and manufacturing and assembly has been made difficult and/or complex. Therefore, it is an object of this invention to provide an improved draw-down vise jaw, relying upon the vise bed or parallels and the like to position the work piece, enclosing all working parts and members to the exclusion of chips and debris, and generally providing a replaceable and readily accessible jaw unit, either hardened or with a machinable soft face, all as circumstances require.
It is the said positioning of a work piece in a vise which is the primary object of this invention. The classic method of setting a work piece is to tap or hammer the same into position, with the result that the work piece is often pre-loaded and thereby deformed. That is for example, a work piece which is not perfect and which is pounded into position in a vise and then machined, will return to its imperfect form when released; and thus the imperfection is not removed by machining. Therefore, it is an object herein to provide jaw alignment during draw-down onto the bed or parallels and which provides positive gripping and which does not pre-load the part, so that any imperfection can be machined away.
With the present invention, the floating jaw elements slide free upon inclined planes of the fixed jaw elements while gripping the work piece to draw it into a seated position upon the bed or parallels, simultaneously compensating for slight variations from parallelism in said work piece. Thus, when a work piece with no taper is gripped the floating jaw elements draw down evenly, however when a tapered work piece is gripped either jaw may tip, to a degree, in order to conform to the taper of the part. A feature is that the bed or parallels supports the work piece while the floating jaw member is free, there being no positive stop therefor, during normal operation.
The accuracy of machine work depends greatly upon cleanliness and the exclusion of chips and debris from the tool elements which determine position of the work piece. This includes vise jaws per se which are the subject of this invention, it being an object herein to provide a fixed and floating jaw combination which excludes all chips and debris. With the present invention, there is a "unit" concept for the repeated accurate positioning of identicle work pieces and wherein two members are engageable at an inclined plane so as to establish a housing which accommodates the ancillary means necessary for mounting and for operation thereof. That is, the mounting screws which fasten the fixed jaw to the abuttment of the bed and to the slide of the vise are housed. And, the return stop means and bias means thereof are also housed, it being an object to provide cooperation between the stop means and bias means which maintains the closed condition of the two jaw members, as a housing. As will be described, the vise jaw members are cooperative to form an enclosure for all means involved, and to the exclusion of chips and debris, leaving all exposed sides thereof free and clear, and the working face uninterrupted. It is also an object to exclude chips and debris from beneath the floating jaw members, between it and the bed; and to this end a compressible filler occupies that interstice.